Sutures are employed to engage tissue to do things such as closing wounds and/or surgical site incisions, or to repair tissue that has torn. When using a suture, it is important to avoid infection. Although surgeries and wound closings are often performed under sterile conditions, surgical-site infections (SSIs) are the third most commonly acquired hospital infection, and may be associated with severe morbidity and mortality. Since more than sixty percent (60%) of SSIs occur in the area of the incision, the use of sutures having antimicrobial properties has the potential to be useful in combating such infections, and ultimately, hopefully improving patient outcomes by reducing the amount and severity of these SSI type infections.
Sutures having antimicrobial properties exist currently. At the present time, the industry leader in the antimicrobial suture market is believed to be Ethicon, a Johnson & Johnson Company. Johnson & Johnson's Ethicon antibacterial sutures rely primarily on a triclosan-type antibiotic agent.
Triclosan is a chlorinated phenolic biocide antiseptic that, according to Johnson & Johnson has a different mode of action than antibiotics. It is a “phenol” with multi-targeted biocidal mechanisms, that is believed to have non-specific effects that act on cell membrane activities to kill undesired microbes. It is also believed that Triclosan blocks the active site of the Enoyl-acyl Carrier Protein Reductase (ENR) that is an essential enzyme in fatty acid synthesis, used in building cellular components and reproduction.
The Ethicon triclosan coated sutures appear to be able to perform their function in a workmanlike manner. To date, published data exists to suggest that Triclosan inhibits bacteria colonization of a suture. See, Ford H R, Jones P., Reblock K, Simpkins D L, “Intra-operative Handling and Wound Healing Characteristics of Coated Polyglatin 910 Antibacterial Suture and Coated Polyglactin 910 Suture” Surg. Infec. 2005; 6; 313-21.
Additionally, an in vivo study of the Triclosan sutures showed that they have a bactericidal activity against staph and inhibitory or bactericidal activity against S Aureus, Methicillin-Resistant S Aureus, MRSA; S Epidermidis (Biofilm-Positive) and E-coli. See, Storch M L, Rothenberger S J, Jacinto G, “Experimental Efficacy Study of Coated VICRYL+Antibacterial Suture in Guinea Pigs Challenged with Staphylococcus Aures”. Surg. Infect. J. 2004; 5; 2A1-288.
Additional information about the Ethicon sutures can be found on Ethicon's web site at http://www.plussutures.com. Additional discussions of Ethicon's antimicrobial sutures can be found in Stephenson, U.S. Pat. No. 4,024,871 (24 May 1997) and Scalzo et al., U.S. Pat. No. 7,513,093 (7 Apr. 2009). In particular, the reader's attention is directed to the prior art discussions in each of these Ethicon patents, as a wide variety of various antimicrobial agents and methods for incorporating antimicrobial agents into sutures are discussed therein. These disclosures are incorporated herein by reference.
In addition to Ethicon, the Tyco Healthcare Group has also been quite active in the antimicrobial suture field. An example of a Tyco suture is discussed in Robey, U.S. Pat. No. 6,878,757 (12 Apr. 2005), that discloses an antimicrobial suture coating that contains a fatty acid Ester salt mixed with a bioabsorbable co-polymer.
Another Tyco patent application is Cohen, U.S. Published Application No. US2007/0010856 A1, having a publication date of 11 Jan. 2007. Cohen's suture includes a plurality of filaments with interstitial spaces defined by the plurality of filaments, and an antimicrobial solution within the interstitial spaces. An antimicrobial coating is placed on at least a portion of the plurality of filaments. The suture is attached to a needle to produce a needle containing suture. The preferred antimicrobial agent used in Cohen is an antiseptic, film-forming polymer, and a salt of a fatty acid ester. Examples of same are given in paragraph [0014] of the Cohen published patent application.
Additionally, a company named Polymedix has developed an antimicrobial suture, for which they recently received a funding grant. The Polymedix suture employs Poly Cide polymers, that are described as “novel defensinminetic compounds,” that are described as synthetic mimetics of the host offense proteins, that, (according to Polymedix) are one of the oldest and most effective antimicrobial defense systems found in humans and virtually all living creatures. These Poly Cides are alleged to have a mechanism of action that directly disrupts the bacterial cell membranes, that makes the development of bacterial resistence unlikely to occur. More information about these sutures can be found on www.polymedix.com. See Polymecix Press Release dated 11 Jun. 2010 “New Grant Supports Development of Antimicrobial Sutures to Combat Infection”. See http://www.newswise.com/articles. No admission or position is taken as to whether the Polemedix compounds constitute prior art to the instant invention.
Silver is another compound having well known antimicrobial properties that has been used to incorporate antimicrobial properties into particular articles. One old example of silver being used in a ligature is shown in A. W. Clark, U.S. Pat. No. 861,231 dated 23 Jul. 1907. Clark created a surgical ligature that was soaked in an antiseptic salt that preferably comprised a iodide of silver as the insoluble salt.
Another example of a use silver in a textile product (non-suture related), to create an antimicrobial textile product containing silver is shown in Ignazio M. Indiano, U.S. Published Patent Application No. 2010/0000196.
Although the above referenced devices no doubt perform their intended function in a workmanlike manner, room for improvement exists. In particular, room for improvement exists in providing an antimicrobial suture, that is both capable of having significant antimicrobial properties, and that can be produced at a reasonable cost, to provide a cost-effective deterrent for the growth of infections.